Solvent



Sept. 12, 19.33. G. H. BUCHANAN S OLVENT Filed Jan. zo, la?

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ATTORNEY 3o non-solvents, such as toluol. Thisis shown by the Patented Sept. l2, 1933 t STAI'ESA PATE gi-,ezasm y soLvEN'r- Guy H. Buchanan, Westfield, vN. J., assignor `to American; Cyanamid Comiwilfly,k New York, NY., a corporation ofMaine u 4 Application January 20, 1927. Serial No. 162,306 13 claims. (C1. 134-49) This invention relates to solvents, more particularly to a solvent for estersof cellulose and the like,'such as cellulose nitrate.V l

Recently there havefcome into 'extensive use lacquers and varnishes having esters of cellulose as a base. Such lacquers have 'considerable' advantage overthe older oleo-resinous varnishes q because they dry more rapidly and because the iinal protecting film is more resistant. The drying of a cellulose lacquer depends upon the evaporation of the solvents and the rate of` drying is varied in practice by selection ofthe solvents and by variation in their proportions; venience. solvents may be 'divided into three groups, the low boilers,rthe medium boilers and the high boilers. The last named group includes are among the more important. ,Butyl propionate an ideal solvent.

135 and 160 C.V y

` YOf the high boiling. solvents in use at..the present time butyl Vpropionate andethyllactate those solvents whose boiling points lie between when pure boils at 145 C. but thearticle of commerce, which is produced from residuesobtained in acetic acid manufacture, is ,a mixture of the butyl esters of several acids,rpropionic, butyric, valerio, etc., and has a boiling range frequently as wide as 125 to 160`C. Another disadvantage of butyl propionate is* the fact thatit doesnot' stand dilution to any large; degree with cheap figures given 4in Table II following.

Ethyl lactate is an'excellent solvent and hasla high dilution ratio to toluol. Theboiling point of pure ethyllactate is 155 C., andtheboiling range oi the commercial material, is comparatively narrow. Although the'boiling point of pure ethyl lactate is only 10 higher than that of butyl propionate, its vapor pressurek at4 atmospheric temperature is very muchil'ower ythan that Y of butyl propionate. This is shown by `the vapor pressure curves given below andwas confirmed by a simple experiment in which the time required for complete evaporation of solvent from a lter paper previously immersed in the liquid was noted. Twenty minutes were required for complete evaporation of the butyl propionate and l e forty. minutes for the ethyl lactate. Slow evaporation isv frequently vdesiredl bythe lacquer manufacturer and in such casesethyl lactate is If, however,l a more rapid hardening of the lacquer lm is required,` a solvent having a higher rate of evaporation vis preferred.` A more rapid rate ofevaporation may be secured by substituting methyl alcohol for ethyl For cony alcohol', producing the methyl ester instead of the ethyl ester, but this,.at the present price of methyl alcohol, adds very considerably to the cost of the solvent Y I have foundvthat the esters of hydroxy, isobutyric and similar acids are 'excellent solvents for nitrocellulose. These-esters may be produced from vacetoneIcyanhydrinY and other cyanhydrins by treatment with hydrochloric acid and the desired alcohol.` Although 4the boilingfpoint of*v the ethyl ester of hydroxy isobutyric acid is given y in the chemical literature as `15d" C. little is said duced I added alcoholic hydrochloric acid and the amount of water required by the chemical equation and heated the mixture untilthe cyan l hydrin was completelyreacted. I then filtered ofi" theprecipitated ammonium chloride', washed it with alcohol, combining the filtrate and the washings, and separated the `esterfroin the excess alcohol by fractional distillation, l z

' The product so `obtained was `'ethyl alpha hydroxy isobutyrate, Vhaving a boiling point of `about 147 y C.

IThe reactions takingplacein the above process are Yprobably in accordance with the following formulas: f

CH3 COO. CiHn-i-NHiCl The following generic structural formulas in-f dicate thewgeneral reactions which take placev and the class of chemical compoundsrformed oi the; dissolved nitrocellulose occurs.

'tests 2 grams of 17/2 second nitrocellulose were diss produced. Thev following A.. obtained.A

, 'Ihe `esters of hydroxy iso-butyric acid are also which I have found suitable for use as solvents d for cellulose esters: Y

in which R',`R and R' represent'the same or diierent aliphatic radicals, and, more particulare ly where they represent methyl or ethyl radicalsl 4 The viscosity of solutions .of nitrocellulose in the solvent is a ymeasure of the relative solvent, powers of the solvent, the solvent producing the least viscous solution being 'thebest solvent. "In

my tests I dissolved 18.3 grams of dry ffoinsec-` ondenitrocellulose in cc. of the solvent'and diluted (with -100 cc. of toluene. Viscositieswere determined ,by the falling ball viscosimeter. The results .of my tests were vas follows: Y

Table I l Ethyl lhydroxy isobutyrate 16.6 seconds Ethyl acetate 12.7 seconds Butyl acetate .601 yseconds Ethyl lactate 9.2 seconds Butylpropionate Too thick for test l solved in 20 cubic centimeters yof solvent and toluol was added until a'permanent turbidity was ratios with toluol were .Table IIV vlithyl hydroxy isobutyrate .6.0

Ethyl lactate 6.7 Butyl propionate 2.5v Butyl acetate 2.5

excellent solvents for other cellulose esters such as cellulose acetate'. The following is a `table of dilution ratios determined as above with the nitrocellulose, dissolving two grams-of cellulose acetate in 2G cubic centimeters "of the solvent, and benzoly *being added to the clear .solutions unt-il a Y permanent turbidity was produced:

Table III Methyl hydroxy isobutyrate 1.30 Y Ethyl hydroxy isobutyrate 0.90 Acetone 0.90 Ethyl acetate .0.25 Ethyl methyl ketone 0.20 Di-acetone alcohol 0.95

vment I added 45% -of water to the ester and heated it in a constanttemperature .bath at C. for eight days. I found that only 0.06% of the ester was hydrolyzed under these severe conditions,

evidencing a stability toward hydrolysis farv in excess of the requirements of practice.

The rate of evaporation of ethyl hydroxy isobutyrate at atmospheric temperatures was determined by exposing weighed portions of the solvent to the air. For comparison, the rate of evaporation lof butyl propionate and Vof ethyl lactate was determined at the same time and under the .same conditions. In the accompanying drawing constituting a part hereof, the single iigure shows 4`afseries of'curves representing the relative rates otevaporation at room temperature of ethyl propionate," ethyl alpha hydroxy isobutyrate and ethyl ."lactate. y The curves indicate that the rate of evaporationof ethyl alpha hydroxy isobutyrate is VinterI-nediate between those of the other two solvents.` Y. Y

I mayV employ` alcohols other than ethyl alcohol inthe production of the esters of hydroxy isobutyric acid and can in this way alter the rateof evaporation of the solvent;` yThus by substitution of methyl alcohol for ethyl ,alcohol I lower the atmospheric boiling 4point by about twelve degrees, methyl hydroxy isobutyrate having a boiling point oi about 1735"'C.v Substitution ofbutyl or amyl alcohol `for `ethyl alcohol raises the boiling point, The esters of all of these alcohols are excellent solvents, change inthe alcohol having comparatively little effect upon the solvent propp orties, the onlyvimportant eiect being `upon the rate 4'of evaporation ofthe esters. y f

V It is also obvious that one may substitute for acetonajwhich' is dimethyl ketone, other ketones 'such as diethyl ketone or methyl ethyl ketone or others Ywithout kdepartingfrom the spirit of the invention. .Also,"although, I have ldismissed the solvent properties of the ester for cellulose 11itrate, I consider my new solvents' suitable for use with 'other esters o'fvcellulose, for example with cellulose acetate. These and other changes may be made in .my inventiom thescope .of which is dened in the claims appended hereto.

What I claim is: f j d y 1. A composition ofvmatter comprising cellulose nitrate and an ester .of alpha hydroxy ,isobutyric acid the ester being a solvent for the `cellulose nitrate.

V2. A composition of matter comprising cellulose `nitrateand theethyl ester of alpha hydroxy iso'- butyric acid. y f

3. A composition of matter comprising .a cellulose ester and an ester of alpha hydroxy isobutyric acid .the latter ester being compatible with the cellulose ester. l. i

4.' A composition of matter comprising a cellulose ester and theethyl .ester of alpha hydroxy iso-butyric acid. n

' 15.A composition of matter comprising a cellugeneric formula:V

Y' I /C\ y l R" y oooR'" w in whichR' vand R represent methyl or ethyl,

and Rm representsan aliphatic radical, the-compound represented by the'formula being a solven of. the cellulose ester. Y

6. The composition of claim 5, in which R', R"

and R!"V represent methyl or ethyl.

'7. The composition of claim 5, in which R and JR :represent ethyl `the compound k:represented by the formula being a solvent for the cellulose ester.

lose ester and a compound having the following,

ico

lio

iis

c. The composition ofv omini 5, in which R' represents methyl and R" represents ethyl the compound represented by the formula. being a,

solvent for the cellulose ester.

9. The composition of claim 5, in which the cellulose ester is nitrocellulose'and in which R and R represent methyl or ethyl the compound represented by the formula. being a. liquid vsolvent fory the nitrocellulose.

10. The composition of claim 5, in which the cellulose ester is nitrocellulose and in which Rf, R" and R'" represent methyl or ethyl.

11. The composition of claim 5, in which the cellulose ester is nitrocellulose and in which R and R" represent ethyl the compound represented bythe formula. being a. liquid the: nitrocellulose.

12,'The composition of claim A5, in which vthe GUY H. BUCHANAN.

solvent for 

